Debate over medical cannabis has been hijacked by "nuisance" campaigners who are making it harder for people with serious diseases, says Associate Health Minister Peter Dunne.

The Government has come under renewed pressure to conduct trials on medicinal cannabis products, while New South Wales Premier Mike Baird said last week he was in support of NSW becoming the first Australian state to legalise medicinal cannabis for terminally ill patients.

Dunne believed there was only a small number of cases where people were "genuinely ill" and that many who lobbied him on the subject were secretly hoping to legalise weed for recreational use.

"There are a lot of people leaping on the bandwagon because they see it as a way of achieving another objective, which has nothing to do with medical cannabis," he said. "They're a nuisance. Sadly what they're doing is muddying the waters for those who may have a genuine case."

The comments have drawn criticism from parents of children with rare diseases who say Dunne has deflected responsibility on the issue.

New Zealand Drug Foundation director Ross Bell said people wanting to access non-psychoactive cannabinoids were not plotting to smoke marijuana.

Dunne's "reflecting a common fear that politicians have that somehow medical cannabis might be a back door to allowing recreational use - but it's a fear that doesn't have a basis in reality."

Bell said those leading the call for medical cannabis weren't "stereotypical law-reform, smoking on the steps of Parliament kinds of guys. They're patient groups, cancer sufferers, people suffering from MS and most recently kids with seizures."

Jessika Guest, who moved from Northland to America in order to get cannabis oil for her six-year-old epileptic daughter, said claims of a hidden agenda were "ridiculous". "That argument is so far beyond what the truth really is, I find it totally ridiculous and ignorant to what's really happening.

"Why would so many people be breaking the law to give cannabis to their children and why would they be so public about it?"

Guest and her children Jade, 6, and Ethan, 8, last week left behind husband Brendan to relocate to Colorado - where cannabis oil is legal. Without a law change in New Zealand the family would not return to their home in Whangarei.

"That's the most frustrating thing for us - we've got the medicine within reach. [Dunne] can sign a piece of paper for one poor dying kid to use CBD cannabis oil but he won't do that."

Dunne said the Ministry of Health has yet to receive any formal requests to run trials of cannabis oil or cannabis liquid products. He said it was up to pharmaceutical companies to run trials for their products, and campaigners should direct their calls to them.

"I think they should be lobbying the manufacturers to seek to have them tested in New Zealand. We can assess the evidence at that point. But until that happens it's all a bit of a guessing game."

Dunne said he was keeping an eye on medical cannabis developments overseas and said decisions from the Law Commission Review of The Misuse of Drugs Act would be released some time in the next year.